Technical Field
The present invention relates to an optical image lens system. More particularly, the present invention relates to a compact optical image lens system applicable to electronic products and three-dimensional (3D) image applications thereof.
Description of Related Art
In recent years, with the popularity of mobile products with camera functionalities, the demand for a miniaturized photographing lens assembly is increasing. The sensor of a conventional photographing camera is typically a CCD (Charge-Coupled Device) image sensor or a CMOS (Complementary Metal-Oxide Semiconductor) sensor. As the advanced semiconductor manufacturing technologies have allowed the pixel size of sensors to be reduced and compact photographing lens assemblies have gradually evolved toward the field of higher megapixels, there is an increasing demand for photographing lens assemblies featuring better image quality.
A conventional compact optical lens system employed in a portable electronic product, such as the one disclosed in U.S. Pat. No. 7,869,142, mainly adopts a four-element lens structure. Due to the popularity of mobile products with high-end specifications, such as smart phones and PDAs (Personal Digital Assistants), the requirements for smaller pixel size and better image quality have been increasing. However, the conventional four-element lens structure cannot satisfy these requirements of the compact optical lens system.
Although other conventional optical lens systems with five-element lens structure such as the ones disclosed in U.S. Pat. Nos. 8,000,030 and 8,000,031 enhance image quality and resolving power, these optical designs still reside with unsolved problems. Since there are no three continuous lens elements closest to the object side with positive refractive power, it is not favorable for presenting its telephoto functionality in which the telephoto ratio is thereby limited. These optical designs are also hard to keep the lens system compact while achieving for the same telephoto ratio. Besides, these optical designs are not favorable for reducing the sensitivity of the lens system because its positive refractive power of these optical systems is not effectively distributed.